Conventionally, as a technique for housing and fixing the substrate in a holding space section of the case, a technique, in which the substrate is pressed against a crush rib that is formed integrally with the case and the crush rib is crushed then the substrate is fixed by its reaction force, has been known by a Patent Document 1.
In addition, in a configuration in which the substrate, the actuator etc. are housed in the holding space section that is formed by joining a first case and a second case, when joining the both cases together, the substrate mounted on the first case is pressed against by the crush rib that protrudes from the second case, and the crush rib is crushed, thereby fixing the substrate.    Patent Document 1: Japanese Patent Application Kokai Publication No. 2005-5168